We suggested recently a novel type of pH-sensitive delivery system, 'fliposomes', which contain trans-2-aminocyclohexanol-based amphiphiles that perform a conformational flip and trigger an instant cargo release in acidic media. Here we report our latest studies on the cellular uptake in HeLa and B16F1 cells of the methotrexate-loaded fliposomes, which indicate that the latter can serve as viable drug delivery systems.